Currently, the solution says "We test that the derivative at a point in the interval, say x = 1 / 2, which gives a value of 6\cdot 2^{7/5}/5(-1/2) < 0 . Thus the function is increasing on this interval."

This should say "decreasing" since it is <0.

Just to clarify any confusion :)

So overall, the function is increasing on (-infinity; 0)U(1, infinity) and decreasing on (0, 1).

KristinaB (talk)00:37, 30 November 2013

Good find, Kristina. Thank you for that, the solution has been updated.

Bernhard Konrad (talk)01:01, 30 November 2013